On March 4, 1970 the French submarine Eurydice exploded, killing all 57 sailors aboard. On the morning of March 4, the French military command lost contact with the Eurydice. At the same time 35 miles east of Toulon, a geophysical laboratory picked up shock waves of an underwater explosion.
The Eurydice was a ship of the Daphné class, diesel-electric patrol submarines built in France between 1958 and 1970 for the French Navy and for export. Two of these subs in this class, the Eurydice in 1970 and the Minerva in 1968 sank due to mechanical accidents.
The cause of the explosion was never officially determined. Several hypotheses have been proposed to explain the sinking of the Eurydice:
1) A collision with a cargo ship;
2) An accidental leak;
3) A faulty snorkel design.